Time switch



y 15, 4 G. o. PUERNER 2,424,116

TIME SWITCH Filed Sept. 7; 1944 uvmvmk. ''mgfe d Mar Patented July 15,1941

UNITED STATES PATENT OFFICE to P. R. Mallory '& 00., Inc., Indianapolis, Ind., a corporation of Delaware Application September 7,1944, Serial No. 552,964

. '1 Claims. 1

The present invention relates to electric switches, and, more particularly, to cam-controlled electric switching devices. v

In U. S. Patent No. 2,313,064 to H. C. Hall, there is disclosed a time switch including a plurality of cams driven by a clock motor and having their outer edges cut out with predetermined notches to actuate a, plurality of contact arms in the desired sequence. In the embodiment of the time switch illustrated in Figures 6, 7 and 8 of the patent there is shown an additional small cam which is rotated comparatively rapidly by the same motor and is provided with a. single notch.

This small cam is supported closely adjacent one of the large cams, with its edge aligned with the edge of the large cam at one point, that point being the point of contact with a cam following lug on the contact arm simultaneously resting upon the peripheries of large and small cam. This arrangement provides for a shorter closed-contact interval than would be obtainable with a large cam alone due to the fact that when a notch in the large cam comes opposite the cam following lug, the lug is not permitted to fall into such notch until the notch in the small cam also comes opposite the said arm. When this occurs, the contacts are closed but, since the small cam is rotating rapidly, the contacts are closed only for a short period and are then reopened by' the further travel of the small cam. In this manner, it is possible to obtain shorter contact-closed periods as well as more rapid opening of the contacts.

The present invention constitutes an improvement over time switches of the described character in that it provides for both long and short closed contact intervals.

It is an object of the present invention to improve time switches of the type described.

Other and further objects andadvantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawing; in which Fig. l is a side elevational view, with parts broken away for reasons of clarity, of a time switch embodying the principles of the present invention;

Fig. 2 is a section taken on line 2-2 of Fig. 1;

Fig. 3 is an end view, somewhat fragmentary in character, and illustrating details of the cams and of the cam followercontact arm; and

Fig. 4 is an exploded perspective view of the cam follower member and of a portion of the contact arm.

While a preferred embodiment of the invention is described herein, it is contemplated that considerable variation may be made in the method of procedure and the construction of parts without departing from the spirit of the invention. In the following description and in the claims, parts will be identified by specific names for convenience, but they are intended to be as generic in their application to similar parts as the art will perrnit.

Referring now more particularly to the drawing, reference character Ill denotes a clock motor which may be of the mechanical or electrical type but is preferably a small synchronous electric motor such as is extensively used in clocks and timing apparatus at the present time. Motor iii is mechanically connected to a gear train mechanism generally denoted by reference character Ii enclosed within a casing l2 and mounted between end plates l3 and II. The said gear train comprises a shaft iI' projecting from the casing of a clock motor Ill and having a pinion l6 ilxed thereon, meshing with gear Ilia and thus driving gear ll and pinion i8. Pinion II in turn meshes with a gear I! rotatably mounted on a pin 20 but being axially displaceable thereon against the pressure of coil spring 2|. A pinion 22 is likewise rotatably mounted on pin 20, independently from gear ill, but is connected therewith for joint rotation by means of spring pawls 23. Pinion 22 meshes with cam gear 24, fixed on cam shaft 25, one end of which is rotatably supported in bearing 26 provided in end plate II. A similar bearing (not shown) may beprovided for the other end of the cam shaft.

Cam shaft 25 has a plurality of large cam discs 21 fixed thereon, preferably constituted of a suitable insulating material, such as Bakelite. These cam discs or cams are provided with notches 22 and with projections 29 at predetermined points on the circumference thereof. An additional small cam 30 with a single notch 3| therein is fixed on shaft [5 upon which the first driving pinion of the gear train is mounted. This small cam is supported closely adjacent one of the large cams 21, with its edge aligned with the edge of the said large cam at one point, that.

35 to the inside face of a supporting insulating plate 3'. The outer or terminal end 31 of the contact arm is bent at right angles through a slot in plate I andproiects throughsaid slot. Terminal end 31 may be provided with soldering ears and holes to facilitate the soldering of connecting conductors thereon. The arm portion of the contact arm is bent inward at right angles to its supporting plate 35 and extends almost clear across the inside of the casing to an opposite insulating plate 38, terminating short of this plate. The contact arm, thus mounted, has its midportion spaced slightly away from the edge of its cooperating cam. The enlargement in the midportion of said arm constituting ears 3| is provided with an oblong opening 35, the object of which will appear presently.

The cam follower member 32, which is preferably integrally formed or molded of insulating material comprises an oblong base or body portion ll with holes 4| at the ends thereof and a depeding cam portion 42 having a wedge-shaped cam surface 43 thereon. (Fig. 4.) Cam portion 42 is extended at one side beyond the lateral edge of body portion 40 and is undercut as indicated at 44 to facilitate its assembly with the midportion of contact arm 33. When assembling the cam follower mechanism, cam portion 42 of member 32 is passed through opening I! in the contact arm and the lower face of body portion II is brought into face to face position with the top surface of the arm so that holes ll are aligned with corresponding holes 45 in the arm. Thereafter, the cam follower member is secured to the contact arm by means of rivets l5 and ears 34 of the arm are bent up against the sides of the follower member to increase the rigidity of the arm in its midportion where it is most subjected to bending stresses.

The free end of contact arm 33 carries contact discs 41 and 43 on its upper and lower surface, respectively. The contact discs are adapted to cooperate with contact discs 48 and II, respectively carried at the ends of stationary contact arms 5| and 52, secured to insulating plate 38 by means of rivet 53. The other ends of both arms 5| and 52 are extended through a slot in insulating plate 38 and constitute the other termine] 54 of the contact system.

From the foregoing description, the operation of the time switch embodying the invention will be readily understood by those skilled in the art. The operation of gear train ll being fully disclosed in the said Patent No. 2,313,064 will not require any detailed description and it will be sumcient to state that it will advance cam shaft and large earns 21 at a predetermined rate, and shaft l5 and small cam thereon at a considerably iaster rate. It i also to be observed at the outset that cam portion 42 of follower member 32 and its lower edge 55 are of a sufiicient width to simultaneously engage the edge of both large cam 21 and of small cam 30.

Since large cam 21 advances slowly in the direction of arrow 56, cam controlled contacts and would ordinarily be closed for a substantial time interval whenever one of notches 25 comes opposite edge of the cam follower member. However, as edge 55 engages both the edge of large cam 21 and of small cam ill, the cam follower edge is not permitted to drop into notch 28 until notch 3| in the small cam also comes opposite the cam follower edge. When this occurs, contacts 48, 50 are closed, but since cam 30 is rotating rapidly, they are closed only for a short 4 p riod and are then reopened y the further travel of cam 30. By the time notch 3| again comes opposite edge 55, large cam 21 has advanced its notch 25 out of position for cooperation with edge 55 and hence the contacts remain open.

When during further rotation of large cam 21 one of projections 29 moves into cooperative position with the cam follower member, contact arm 33 will be lifted up and its contact I! will close with stationary contact 43. As this contact closing operation is not affected in any way by the rotation of small cam 30, contacts 41 and 0 will remain closed for a period which is considerably longer than that of contacts 45, ll. As both contacts '48 and 50 are connected to the same terminal 54, both short and long contact closing periods will be effective in the same controlled circuit although, of course, the said contact closing periods of different duration may be made effective in two independent circuits with obvious modifications of the contact system.

It will be noted that the time switch embodying the principles of the invention provides various important advantages. Thus, first of all, the time switch of the invention permits obtaining a a greater freedom in the selection of contact closing periods as both short and long periods may be provided in any desired predetermined sequence. For example, projections 23 may be designed to produce contact closing for a full impuse time, such as 60 seconds, or multiples thereof while notches 28 in cooperation with notch ll of the small cam may produce contact closing for a fractional impulse time such as 15 seconds. This makes possible any number of 60 second contact makes, up to one-half of total impulses, in addition to any number, up to one-half total impulses, of the same contact "make" for a shorter period, where all the shorter periods are uniform.

It is also to be observed that the improved time switch is very simple in construction and its principles may be readily applied to switches of the described general type without requiring any retooling or expensive structural changes.

Although the present invention has been disclosed in connection with a preferred embodiment thereof, variations and modifications may be resorted to by those skilled in the art without departing from the principles of the present invention. Thus, while in the illustrated embodiment the slow and fast cams are advanced continuously, the large cams may be periodically rapidly rotated through a predetermined angle and may remain at rest between the periods of rotation. as is disclosed in Patent No. 2,227,133 to H. C. Hall. The small and large cams, preferably made of an insulating material, such as Bakelite, may be also made of metal, in view or the insulative character of cam follower member 32. Obviously, any desired number of cam discs and contact arms may be provided to suit the specific application.

All these variations and modifications are considered to be within the true spirit and scope of the present invention, as disclosed in the foregoing description and defined by the appended claims.

What is claimed is:

l. A time switch comprising in combination a drive motor, a gear train driven thereby, a cam driven by said gear train, a. second cam driven at a different speed by said gear train, a set of electrical contacts under Joint control of both said 5 cams, and a set of electrical contacts under in divldual control of one of said cams.

2. A time switch comprising in combination a drive motor, a geartrain driven thereby, a first cam driven by said gear train at a relatively slow rate, a second cam driven by said gear train at a considerably faster rate, a set of electric contacts under simultaneous control of both said cams whereby actuation of said contacts for short periods is initiated only when permitted by both cams jointly, and a second set of electric contacts under individual control of said first cam whereby actuation of said contacts for relatively long periods is initiated by said first cam alone. n

3. A time switch comprising in combination a drive motor, a gear train driven thereby, a first cam driven by said gear train at a relatively slow rate and having cut out portions and raised portions on its cam surface, a second cam driven by said gear train at a faster rate and having a. cut out portion on its cam surface, a cam follower arm engaging the cam surfaces of both cams, and electric contacts respectively operable by upward and downward displacement of said arm whereby one of said contacts is operated for short periods when the said arm drops into the aligned cut out portions of both cams and the other of said contacts is operated for longer periods when said arm is lifted up by one of the raised portions of the first cam.

4. In a time switch including a notched slow cam and a notched fast cam and cam follower contact arm capable of actuation in predetermined positions of both cams when said arm simultaneously enters notches of said cams, the improvement which comprises at least one protruding portion on said slow cam, and contact means operable by said arm when the arm is lifted up by said portion.

5. In a time switch including a slow and a fast circular cam each having at least one notch thereon and a cam follower contact arm capable of actuation to close with a first contact for short periods when said arm simultaneously enters notches of both cams in predetermined positions thereof, the improvement which comprises at least one projection on said slow cam, and a second contact electrically connected with said first contact and closing with said contact arm for a long period when said arm is lifted up by the proiection on said slow cam. 1

6 6. The time switch according to claim 3 wherein the cam follower arm comprises a strip of spring metal clamped at one end thereof and bearing contact discs at the other end thereof,

said strip having a widened midportion with an opening therein, a cam follower member integrally formed of insulating material having a flat body portion secured to said strip and a camengaging portion extending through said opening in the strip and of sufficient width to engage both cams of the time switch, and ears defined in the widened mid-portion of the said strip bent up against the side edges of the cam follower member to reinforce the resulting structure.

7. In a time switch for obtaining both short and long operation periods in a circuit, a first cam having at least one cut out portion and one raised portion on its cam surface, a cam following arm for normally engaging an intermediate portion of said cam surface, a first set of contacts operable by said arm when it is displaced from its normal position by a raised portion, a second set of contacts operable by said arm when it moves from its normal position into engagement with a cut out portion, a second cam for restoring said arm to its normal position a short interval after it has been displaced by engagement with a cut out portion, means for moving the second cam rapidly and the first cam more slowly so that both sets of contacts are intermittently closed for periods of relatively long duration when the cam follower arm is operated only by said first cam and the second set of contacts is intermittently closed for periods of relatively short duration when the arm is operated by both of said cams.

GEORGE 0. PUERNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

